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</a></div> <!----></nav> <!----> </aside> <div class="password-shadow password-wrapper-in" style="display:none;" data-v-5cb9a64e data-v-0c5314fc><h3 class="title" style="display:none;" data-v-5cb9a64e data-v-5cb9a64e>数据结构与算法---链表---双向链表</h3> <!----> <label id="box" class="inputBox" style="display:none;" data-v-5cb9a64e data-v-5cb9a64e><input type="password" value="" data-v-5cb9a64e> <span data-v-5cb9a64e>Konck! Knock!</span> <button data-v-5cb9a64e>OK</button></label> <div class="footer" style="display:none;" data-v-5cb9a64e data-v-5cb9a64e><span data-v-5cb9a64e><i class="iconfont reco-theme" data-v-5cb9a64e></i> <a target="blank" href="https://vuepress-theme-reco.recoluan.com" data-v-5cb9a64e>vuePress-theme-reco</a></span> <span data-v-5cb9a64e><i class="iconfont reco-copyright" data-v-5cb9a64e></i> <a data-v-5cb9a64e><span data-v-5cb9a64e>茂茂</span>
            
          <span data-v-5cb9a64e>2019 - </span>
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        </a></span></div></div></div> <div data-v-0c5314fc><main class="page" style="padding-right:0;"><div class="page-title" style="display:none;"><h1 class="title">数据结构与算法---链表---双向链表</h1> <div class="page-info" data-v-0efa1f05><i class="iconfont reco-account" data-v-0efa1f05><span data-v-0efa1f05>茂茂</span></i> <i class="iconfont reco-date" data-v-0efa1f05><span data-v-0efa1f05>2023-03-22</span></i> <i class="iconfont reco-eye" data-v-0efa1f05><span id="/blog/blogs/tec/2023/032201.html" data-flag-title="Your Article Title" class="leancloud-visitors" data-v-0efa1f05><a class="leancloud-visitors-count" style="font-size:.9rem;font-weight:normal;color:#999;"></a></span></i> <i class="iconfont reco-tag tags" data-v-0efa1f05><span class="tag-item" data-v-0efa1f05>数据结构与算法</span></i></div></div> <div class="theme-reco-content content__default" style="display:none;"><h2 id="双向链表"><a href="#双向链表" class="header-anchor">#</a> 双向链表</h2> <blockquote><p>节点除了存储数据外，还有两个指针分别指向前一个节点地址（前驱指针prev）和下一个节点地址（后继指针next）。</p></blockquote> <img src="/blog/image-20221124153552974.png" alt="双向链表"> <img src="/blog/image-20221130115202342.png" alt="双向链表"> <div class="language-js extra-class"><pre class="language-js"><code>    <span class="token operator">&lt;</span>script<span class="token operator">&gt;</span>
        <span class="token keyword">class</span> <span class="token class-name">Node</span> <span class="token punctuation">{</span>
            <span class="token function">constructor</span><span class="token punctuation">(</span><span class="token parameter">element</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token keyword">this</span><span class="token punctuation">.</span>element  <span class="token operator">=</span>element<span class="token punctuation">;</span>
                <span class="token keyword">this</span><span class="token punctuation">.</span>next <span class="token operator">=</span> <span class="token keyword">null</span><span class="token punctuation">;</span>
            <span class="token punctuation">}</span>
        <span class="token punctuation">}</span>

        <span class="token keyword">class</span> <span class="token class-name">LinkedList</span><span class="token punctuation">{</span>
            <span class="token comment">//#</span>
            <span class="token function">constructor</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token keyword">this</span><span class="token punctuation">.</span>count <span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>
                <span class="token keyword">this</span><span class="token punctuation">.</span>head <span class="token operator">=</span> <span class="token keyword">null</span>
            <span class="token punctuation">}</span>

            <span class="token comment">//push</span>
            <span class="token function">push</span><span class="token punctuation">(</span><span class="token parameter">element</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token keyword">const</span> node <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Node</span><span class="token punctuation">(</span>element<span class="token punctuation">)</span>
                <span class="token comment">// console.log(node)</span>

                <span class="token comment">//header是空</span>
                <span class="token keyword">if</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">.</span>head <span class="token operator">===</span><span class="token keyword">null</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                    <span class="token keyword">this</span><span class="token punctuation">.</span>head <span class="token operator">=</span> node
                <span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span>
                    <span class="token keyword">let</span> current <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span>head

                    <span class="token keyword">while</span><span class="token punctuation">(</span>current<span class="token punctuation">.</span>next<span class="token operator">!==</span><span class="token keyword">null</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                        current <span class="token operator">=</span> current<span class="token punctuation">.</span>next
                    <span class="token punctuation">}</span>
                    current<span class="token punctuation">.</span>next <span class="token operator">=</span> node

                    <span class="token comment">// console.log()</span>
                <span class="token punctuation">}</span>

                <span class="token keyword">this</span><span class="token punctuation">.</span>count<span class="token operator">++</span>
            <span class="token punctuation">}</span>
            <span class="token comment">//指定位置删除</span>
            <span class="token function">removeAt</span><span class="token punctuation">(</span><span class="token parameter">index</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token keyword">if</span><span class="token punctuation">(</span>index<span class="token operator">&gt;=</span><span class="token number">0</span> <span class="token operator">&amp;&amp;</span> index<span class="token operator">&lt;</span><span class="token keyword">this</span><span class="token punctuation">.</span>count<span class="token punctuation">)</span><span class="token punctuation">{</span>
                    <span class="token keyword">let</span> current  <span class="token operator">=</span><span class="token keyword">this</span><span class="token punctuation">.</span>head
                    <span class="token keyword">if</span><span class="token punctuation">(</span>index<span class="token operator">===</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                        <span class="token keyword">this</span><span class="token punctuation">.</span>head <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span>head<span class="token punctuation">.</span>next
                    <span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span>
                        <span class="token keyword">let</span> previous 
                        
                        <span class="token keyword">for</span><span class="token punctuation">(</span> <span class="token keyword">let</span> i<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>i<span class="token operator">&lt;</span>index<span class="token punctuation">;</span>i<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                            previous <span class="token operator">=</span> current
                            current <span class="token operator">=</span> current<span class="token punctuation">.</span>next
                        <span class="token punctuation">}</span>

                        previous<span class="token punctuation">.</span>next <span class="token operator">=</span> current<span class="token punctuation">.</span>next
                    <span class="token punctuation">}</span>
                    <span class="token keyword">this</span><span class="token punctuation">.</span>count<span class="token operator">--</span>
                    <span class="token keyword">return</span> current<span class="token punctuation">.</span>element
                <span class="token punctuation">}</span>

                <span class="token keyword">return</span> 
            <span class="token punctuation">}</span>

            <span class="token function">getNodeAt</span><span class="token punctuation">(</span><span class="token parameter">index</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token keyword">if</span><span class="token punctuation">(</span>index<span class="token operator">&gt;=</span><span class="token number">0</span><span class="token operator">&amp;&amp;</span> index<span class="token operator">&lt;</span><span class="token keyword">this</span><span class="token punctuation">.</span>count<span class="token punctuation">)</span><span class="token punctuation">{</span>
                    <span class="token keyword">let</span> node <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span>head

                    <span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">let</span> i<span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span>i<span class="token operator">&lt;</span>index<span class="token punctuation">;</span>i<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                        node <span class="token operator">=</span> node<span class="token punctuation">.</span>next
                    <span class="token punctuation">}</span>
                    <span class="token keyword">return</span> node
                <span class="token punctuation">}</span>
                <span class="token keyword">return</span> 
            <span class="token punctuation">}</span>

            <span class="token function">removeAt2</span><span class="token punctuation">(</span><span class="token parameter">index</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token keyword">if</span><span class="token punctuation">(</span>index<span class="token operator">&gt;=</span><span class="token number">0</span> <span class="token operator">&amp;&amp;</span> index<span class="token operator">&lt;</span><span class="token keyword">this</span><span class="token punctuation">.</span>count<span class="token punctuation">)</span><span class="token punctuation">{</span>
                    <span class="token keyword">let</span> current  <span class="token operator">=</span><span class="token keyword">this</span><span class="token punctuation">.</span>head
                    <span class="token keyword">if</span><span class="token punctuation">(</span>index<span class="token operator">===</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                        <span class="token keyword">this</span><span class="token punctuation">.</span>head <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span>head<span class="token punctuation">.</span>next
                    <span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span>
                        <span class="token keyword">let</span> previous <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">getNodeAt</span><span class="token punctuation">(</span>index<span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">)</span>
                        current  <span class="token operator">=</span> previous<span class="token punctuation">.</span>next
                        previous<span class="token punctuation">.</span>next <span class="token operator">=</span> current<span class="token punctuation">.</span>next
                    <span class="token punctuation">}</span>
                    <span class="token keyword">this</span><span class="token punctuation">.</span>count<span class="token operator">--</span>
                    <span class="token keyword">return</span> current<span class="token punctuation">.</span>element
                <span class="token punctuation">}</span>
                <span class="token keyword">return</span> 
            <span class="token punctuation">}</span>

            <span class="token function">equalFn</span><span class="token punctuation">(</span><span class="token parameter">a<span class="token punctuation">,</span>b</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token comment">// return a === b </span>
                <span class="token comment">// 1. 判断是对象， 对象1[key] === 对象2[key]</span>
                <span class="token comment">// 2. 之前基础上， 写一个递归函数， 深度检查是否相等</span>

                <span class="token keyword">return</span> <span class="token constant">JSON</span><span class="token punctuation">.</span><span class="token function">stringify</span><span class="token punctuation">(</span>a<span class="token punctuation">)</span> <span class="token operator">===</span> <span class="token constant">JSON</span><span class="token punctuation">.</span><span class="token function">stringify</span><span class="token punctuation">(</span>b<span class="token punctuation">)</span>

                <span class="token comment">// imumutable （kerwin React视频）</span>
            <span class="token punctuation">}</span>
            
            <span class="token function">indexOf</span><span class="token punctuation">(</span><span class="token parameter">element</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token keyword">let</span> current <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span>head
                <span class="token keyword">for</span><span class="token punctuation">(</span><span class="token keyword">let</span> i <span class="token operator">=</span><span class="token number">0</span><span class="token punctuation">;</span> i<span class="token operator">&lt;</span><span class="token keyword">this</span><span class="token punctuation">.</span>count<span class="token punctuation">;</span>i<span class="token operator">++</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                    <span class="token keyword">if</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">equalFn</span><span class="token punctuation">(</span>element<span class="token punctuation">,</span>current<span class="token punctuation">.</span>element<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                       <span class="token keyword">return</span> i 
                    <span class="token punctuation">}</span>
                    current <span class="token operator">=</span> current<span class="token punctuation">.</span>next
                <span class="token punctuation">}</span>

                <span class="token keyword">return</span> <span class="token operator">-</span><span class="token number">1</span>
            <span class="token punctuation">}</span>
            <span class="token function">remove</span><span class="token punctuation">(</span><span class="token parameter">element</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token comment">// 根据数据 返回索引的方法</span>
                <span class="token keyword">const</span> index <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">indexOf</span><span class="token punctuation">(</span>element<span class="token punctuation">)</span>
                <span class="token keyword">return</span> <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">removeAt</span><span class="token punctuation">(</span>index<span class="token punctuation">)</span>
            <span class="token punctuation">}</span>

            <span class="token function">insert</span><span class="token punctuation">(</span><span class="token parameter">element<span class="token punctuation">,</span>index</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token comment">// 500 , 5</span>
                <span class="token keyword">if</span><span class="token punctuation">(</span>index<span class="token operator">&gt;=</span><span class="token number">0</span><span class="token operator">&amp;&amp;</span> index<span class="token operator">&lt;=</span><span class="token keyword">this</span><span class="token punctuation">.</span>count<span class="token punctuation">)</span><span class="token punctuation">{</span>
                    <span class="token keyword">const</span> node <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">Node</span><span class="token punctuation">(</span>element<span class="token punctuation">)</span>
                    <span class="token keyword">if</span><span class="token punctuation">(</span>index<span class="token operator">===</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                        <span class="token comment">//this.head</span>
                        <span class="token keyword">const</span> current <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span>head
                        node<span class="token punctuation">.</span>next <span class="token operator">=</span> current
                        <span class="token keyword">this</span><span class="token punctuation">.</span>head <span class="token operator">=</span> node
                    <span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span>
                        <span class="token keyword">const</span> previous <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">getNodeAt</span><span class="token punctuation">(</span>index<span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">)</span>
                        <span class="token keyword">const</span> current <span class="token operator">=</span> previous<span class="token punctuation">.</span>next

                        node<span class="token punctuation">.</span>next  <span class="token operator">=</span> current
                        previous<span class="token punctuation">.</span>next <span class="token operator">=</span> node
                    <span class="token punctuation">}</span>

                    <span class="token keyword">this</span><span class="token punctuation">.</span>count<span class="token operator">++</span>
                    <span class="token keyword">return</span> <span class="token boolean">true</span>
                <span class="token punctuation">}</span>

                <span class="token keyword">return</span> <span class="token boolean">false</span>
            <span class="token punctuation">}</span>

            <span class="token function">isEmpty</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token keyword">return</span> <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">size</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token operator">===</span><span class="token number">0</span>
            <span class="token punctuation">}</span>

            <span class="token function">size</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token keyword">return</span> <span class="token keyword">this</span><span class="token punctuation">.</span>count
            <span class="token punctuation">}</span>

            <span class="token function">getHead</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token keyword">return</span> <span class="token keyword">this</span><span class="token punctuation">.</span>head
            <span class="token punctuation">}</span>
        <span class="token punctuation">}</span>

        <span class="token comment">// var list = new LinkedList()</span>
    <span class="token operator">&lt;</span><span class="token operator">/</span>script<span class="token operator">&gt;</span>

    <span class="token operator">&lt;</span>script<span class="token operator">&gt;</span>
        <span class="token keyword">class</span> <span class="token class-name">DoublyNode</span> <span class="token keyword">extends</span> <span class="token class-name">Node</span><span class="token punctuation">{</span>
            <span class="token function">constructor</span><span class="token punctuation">(</span><span class="token parameter">element</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token keyword">super</span><span class="token punctuation">(</span>element<span class="token punctuation">)</span>

                <span class="token keyword">this</span><span class="token punctuation">.</span>prev <span class="token operator">=</span> <span class="token keyword">null</span>
            <span class="token punctuation">}</span>
        <span class="token punctuation">}</span>

        <span class="token keyword">class</span> <span class="token class-name">DoublyLinkedList</span> <span class="token keyword">extends</span> <span class="token class-name">LinkedList</span><span class="token punctuation">{</span>
            <span class="token function">constructor</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token keyword">super</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
                <span class="token keyword">this</span><span class="token punctuation">.</span>tail <span class="token operator">=</span> <span class="token keyword">null</span>
            <span class="token punctuation">}</span>

            <span class="token function">push</span><span class="token punctuation">(</span><span class="token parameter">element</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token keyword">const</span> node <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">DoublyNode</span><span class="token punctuation">(</span>element<span class="token punctuation">)</span>
                <span class="token comment">//prev next</span>
                <span class="token keyword">if</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">.</span>head<span class="token operator">===</span><span class="token keyword">null</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                    <span class="token keyword">this</span><span class="token punctuation">.</span>head <span class="token operator">=</span> node
                    <span class="token keyword">this</span><span class="token punctuation">.</span>tail <span class="token operator">=</span> node
                <span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span>
                    <span class="token keyword">this</span><span class="token punctuation">.</span>tail<span class="token punctuation">.</span>next <span class="token operator">=</span> node
                    node<span class="token punctuation">.</span>prev <span class="token operator">=</span><span class="token keyword">this</span><span class="token punctuation">.</span>tail
                    <span class="token keyword">this</span><span class="token punctuation">.</span>tail <span class="token operator">=</span> node 
                <span class="token punctuation">}</span>

                <span class="token keyword">this</span><span class="token punctuation">.</span>count<span class="token operator">++</span>
            <span class="token punctuation">}</span>

            <span class="token function">insert</span><span class="token punctuation">(</span><span class="token parameter">element<span class="token punctuation">,</span>index</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token keyword">if</span><span class="token punctuation">(</span>index<span class="token operator">&gt;=</span><span class="token number">0</span><span class="token operator">&amp;&amp;</span> index<span class="token operator">&lt;=</span><span class="token keyword">this</span><span class="token punctuation">.</span>count<span class="token punctuation">)</span><span class="token punctuation">{</span>
                    <span class="token keyword">const</span> node <span class="token operator">=</span> <span class="token keyword">new</span> <span class="token class-name">DoublyNode</span><span class="token punctuation">(</span>element<span class="token punctuation">)</span>
                    <span class="token keyword">let</span> current <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span>head
                    <span class="token keyword">if</span><span class="token punctuation">(</span>index<span class="token operator">===</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                        <span class="token keyword">if</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">.</span>head<span class="token operator">===</span><span class="token keyword">null</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                            <span class="token keyword">this</span><span class="token punctuation">.</span>head <span class="token operator">=</span> node<span class="token punctuation">;</span>
                            <span class="token keyword">this</span><span class="token punctuation">.</span>tail <span class="token operator">=</span> node<span class="token punctuation">;</span>
                        <span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span>
                            node<span class="token punctuation">.</span>next <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span>head<span class="token punctuation">;</span>
                            <span class="token keyword">this</span><span class="token punctuation">.</span>head<span class="token punctuation">.</span>prev  <span class="token operator">=</span> node

                            <span class="token keyword">this</span><span class="token punctuation">.</span>head <span class="token operator">=</span> node
                        <span class="token punctuation">}</span>
                    <span class="token punctuation">}</span><span class="token keyword">else</span> <span class="token keyword">if</span><span class="token punctuation">(</span>index<span class="token operator">===</span><span class="token keyword">this</span><span class="token punctuation">.</span>count<span class="token punctuation">)</span><span class="token punctuation">{</span>
                        current <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span>tail
                        current<span class="token punctuation">.</span>next <span class="token operator">=</span> node
                        node<span class="token punctuation">.</span>prev <span class="token operator">=</span> current
                        <span class="token keyword">this</span><span class="token punctuation">.</span>tail <span class="token operator">=</span> node
                    <span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span>
                        <span class="token keyword">const</span> previous <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">getNodeAt</span><span class="token punctuation">(</span>index<span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">)</span>
                        current <span class="token operator">=</span> previous<span class="token punctuation">.</span>next

                        node<span class="token punctuation">.</span>next <span class="token operator">=</span> current
                        current<span class="token punctuation">.</span>prev <span class="token operator">=</span> node
                        previous<span class="token punctuation">.</span>next <span class="token operator">=</span> node
                        node<span class="token punctuation">.</span>prev <span class="token operator">=</span> previous
                    <span class="token punctuation">}</span>

                    <span class="token keyword">this</span><span class="token punctuation">.</span>count<span class="token operator">++</span>
                    <span class="token keyword">return</span> <span class="token boolean">true</span>
                <span class="token punctuation">}</span>
                <span class="token keyword">return</span> <span class="token boolean">false</span>
            <span class="token punctuation">}</span>

            <span class="token function">removeAt</span><span class="token punctuation">(</span><span class="token parameter">index</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token keyword">if</span><span class="token punctuation">(</span>index<span class="token operator">&gt;=</span><span class="token number">0</span> <span class="token operator">&amp;&amp;</span> index<span class="token operator">&lt;</span><span class="token keyword">this</span><span class="token punctuation">.</span>count<span class="token punctuation">)</span><span class="token punctuation">{</span>
                    <span class="token keyword">let</span> current <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span>head
                    <span class="token keyword">if</span><span class="token punctuation">(</span>index<span class="token operator">===</span><span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                        <span class="token keyword">this</span><span class="token punctuation">.</span>head <span class="token operator">=</span> current<span class="token punctuation">.</span>next
                        <span class="token keyword">if</span><span class="token punctuation">(</span><span class="token keyword">this</span><span class="token punctuation">.</span>count<span class="token operator">===</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                            <span class="token keyword">this</span><span class="token punctuation">.</span>tail <span class="token operator">=</span> <span class="token keyword">null</span>
                        <span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span>
                            <span class="token keyword">this</span><span class="token punctuation">.</span>head<span class="token punctuation">.</span>prev <span class="token operator">=</span> <span class="token keyword">undefined</span>
                        <span class="token punctuation">}</span>
                    <span class="token punctuation">}</span><span class="token keyword">else</span> <span class="token keyword">if</span><span class="token punctuation">(</span>index<span class="token operator">===</span><span class="token keyword">this</span><span class="token punctuation">.</span>count<span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                        current <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span>tail<span class="token punctuation">;</span>
                        <span class="token keyword">this</span><span class="token punctuation">.</span>tail <span class="token operator">=</span> current<span class="token punctuation">.</span>prev

                        <span class="token keyword">this</span><span class="token punctuation">.</span>tail<span class="token punctuation">.</span>next <span class="token operator">=</span> <span class="token keyword">undefined</span><span class="token punctuation">;</span>
                    <span class="token punctuation">}</span><span class="token keyword">else</span><span class="token punctuation">{</span>
                        <span class="token keyword">let</span> previous <span class="token operator">=</span> <span class="token keyword">this</span><span class="token punctuation">.</span><span class="token function">getNodeAt</span><span class="token punctuation">(</span>index<span class="token operator">-</span><span class="token number">1</span><span class="token punctuation">)</span>
                        current  <span class="token operator">=</span> previous<span class="token punctuation">.</span>next
                        previous<span class="token punctuation">.</span>next <span class="token operator">=</span> current<span class="token punctuation">.</span>next

                        current<span class="token punctuation">.</span>next<span class="token punctuation">.</span>prev <span class="token operator">=</span> previous<span class="token punctuation">;</span>
                    <span class="token punctuation">}</span>

                    <span class="token keyword">this</span><span class="token punctuation">.</span>count<span class="token operator">--</span><span class="token punctuation">;</span>
                    <span class="token keyword">return</span> current<span class="token punctuation">.</span>element
                <span class="token punctuation">}</span>
                <span class="token keyword">return</span> 
            <span class="token punctuation">}</span>

        
            <span class="token function">getHead</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token keyword">return</span> <span class="token keyword">this</span><span class="token punctuation">.</span>head
            <span class="token punctuation">}</span>

            <span class="token function">getTail</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">{</span>
                <span class="token keyword">return</span> <span class="token keyword">this</span><span class="token punctuation">.</span>tail
            <span class="token punctuation">}</span>
        <span class="token punctuation">}</span>

        <span class="token keyword">var</span> list <span class="token operator">=</span><span class="token keyword">new</span> <span class="token class-name">DoublyLinkedList</span><span class="token punctuation">(</span><span class="token punctuation">)</span>
    <span class="token operator">&lt;</span><span class="token operator">/</span>script<span class="token operator">&gt;</span>
</code></pre></div></div> <footer class="page-edit" style="display:none;"><!----> <div class="last-updated"><span class="prefix">Last Updated: </span> <span class="time">2023/3/22 下午2:59:36</span></div></footer> <!----> <!----> <!----></main> <!----></div></div></div></div></div><div class="global-ui"><div class="back-to-ceiling" style="right:1rem;bottom:6rem;width:2.5rem;height:2.5rem;border-radius:.25rem;line-height:2.5rem;display:none;" data-v-c6073ba8 data-v-c6073ba8><svg t="1574745035067" viewBox="0 0 1024 1024" version="1.1" xmlns="http://www.w3.org/2000/svg" p-id="5404" class="icon" data-v-c6073ba8><path d="M526.60727968 10.90185116a27.675 27.675 0 0 0-29.21455937 0c-131.36607665 82.28402758-218.69155461 228.01873535-218.69155402 394.07834331a462.20625001 462.20625001 0 0 0 5.36959153 69.94390903c1.00431239 6.55289093-0.34802892 13.13561351-3.76865779 18.80351572-32.63518765 54.11355614-51.75690182 118.55860487-51.7569018 187.94566865a371.06718723 371.06718723 0 0 0 11.50484808 91.98906777c6.53300375 25.50556257 41.68394495 28.14064038 52.69160883 4.22606766 17.37162448-37.73630017 42.14135425-72.50938081 72.80769204-103.21549295 2.18761121 3.04276886 4.15646224 6.24463696 6.40373557 9.22774369a1871.4375 1871.4375 0 0 0 140.04691725 5.34970492 1866.36093723 1866.36093723 0 0 0 140.04691723-5.34970492c2.24727335-2.98310674 4.21612437-6.18497483 6.3937923-9.2178004 30.66633723 30.70611158 55.4360664 65.4791928 72.80769147 103.21549355 11.00766384 23.91457269 46.15860503 21.27949489 52.69160879-4.22606768a371.15156223 371.15156223 0 0 0 11.514792-91.99901164c0-69.36717486-19.13165746-133.82216804-51.75690182-187.92578088-3.42062944-5.66790279-4.76302748-12.26056868-3.76865837-18.80351632a462.20625001 462.20625001 0 0 0 5.36959269-69.943909c-0.00994388-166.08943902-87.32547796-311.81420293-218.6915546-394.09823051zM605.93803103 357.87693858a93.93749974 93.93749974 0 1 1-187.89594924 6.1e-7 93.93749974 93.93749974 0 0 1 187.89594924-6.1e-7z" p-id="5405" data-v-c6073ba8></path><path d="M429.50777625 765.63860547C429.50777625 803.39355007 466.44236686 1000.39046097 512.00932183 1000.39046097c45.56695499 0 82.4922232-197.00623328 82.5015456-234.7518555 0-37.75494459-36.9345906-68.35043303-82.4922232-68.34111062-45.57627738-0.00932239-82.52019037 30.59548842-82.51086798 68.34111062z" p-id="5406" data-v-c6073ba8></path></svg></div><div class="kanbanniang" data-v-5775ee02><div class="banniang-container" style="display:;" data-v-5775ee02><div class="messageBox" style="right:68px;bottom:190px;display:none;" data-v-5775ee02>
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